Last month I wrote some about making a notch filter for the AM band. However, before you have any signals to notch out, you must first, of course, have some signal to begin with. Let’s talk a little ...

In this application note we will explore antenna theory and design using EZNEC, an easy-to-use antenna simulator. We will measure the antenna’s characteristic impedance through our application board.

Using digital techniques has caused a resurgence of interest in VLF — very low frequency — radio. Thanks to software-defined radio, you no longer need huge coils. However, you still need a suitable ...